Two stalled franchises forced the guidance cut, and they sit outside the three quarters of revenue management still expects to grow at its long-run pace, with the shares now near the bottom of their decade on sales.

Boston Scientific (BSX) has lost more than half its value over the past year, and the reason is unusually narrow. WATCHMAN and electrophysiology, its two former growth engines, slowed sharply enough to force a cut to the 2026 outlook. The stock now trades at 3.5 times sales. The question is how much of this company that price condemns.

Two Franchises Broke, And One Is Under A Tenth Of Sales

In WATCHMAN, its stroke-prevention implant, the U.S. market slowed sharply and unexpectedly as nine months of new clinical evidence changed which patients get referred; global WATCHMAN sales are guided to fall mid- to high-single digits in the second half of 2026, with no recovery assumed in 2027. In electrophysiology, the company undercalled how much share rival launches would take once PFA, the ablation category its FARAPULSE platform leads, reached roughly 80% of the U.S. AFib market, leaving little conversion left to offset it. Neither problem is the whole company: WATCHMAN, by management's own account, is less than a tenth of revenue, and both sit outside the three quarters of revenue still expected to grow.

Three-Quarters Of Revenue Is Still Guided To Grow About 6%

Management expects the units outside those two, roughly 75% of revenue, to grow about 6% in the second half of 2026, the pace they have held for many quarters. The quarter ended in June showed the spread: Interventional Cardiology grew 15% organically on coronary imaging and complex PCI work, and Endoscopy grew 7%, while Cardiac Rhythm Management declined 2% and Urology grew 1%. Operating margin over the past twelve months is 21%, up from 18.3% a year earlier, so profit widened while the growth story narrowed. Growth that steady, with margins behind it, is one thing the Trefis High Quality Portfolio insists on.

The Sales Multiple Sits Near A Ten-Year Floor

The broken part is small; the discount is not. At 3.5 times sales, against a ten-year low of 3.0 and a high of 8.6, the stock sits nearer the floor of its own decade than its middle. A multiple that low appears to give little credit for the three quarters still compounding, so the trouble merely staying contained would be enough to matter. Nor is the company waiting: it bought back about 40 million shares in the June quarter, and is targeting roughly $500 million of annual run-rate savings by the end of 2029.

Two Lines To Watch, Starting With Stand-Alone WATCHMAN

None of that makes 2027 comfortable. Management expects limited adjusted EPS growth in 2027 and says improving operating margins will be a challenge. So the case is not that the trouble has passed; it is that the price appears to assume it spreads. The clearest of the two lines is stand-alone WATCHMAN procedures in the U.S., which fell in the low teens year over year in the June quarter and which management has assumed will not recover. The other is electrophysiology's global growth, guided to flat in the second half of 2026. If either turns up, the discount loses the trend that created it. Whether a fall this size is opportunity or warning is easier to judge against how this drawdown ranks among every other one on offer.

How Big Should A High Conviction Position Actually Be?

A strong signal is worth acting on, just not with more of your net worth than one surprise could undo. Either way, a position that has grown large enough to matter is worth sizing deliberately rather than by accident. What a position that size would do to your net worth is exactly what the Trefis Wealth team computes, with the same rules-based systematic discipline that runs our High Quality Portfolio. Request a free vulnerability audit of your biggest positions.